Mon-Fri 9am-9pm
Sat-Sun 9am-6pm
May 21 9am-6pm

Insect Pests on Fruits

Apple Maggot
Cherry Fruit Fly
Gooseberry Sawfly
Saskatoon Sawfly
Wasp Damage


Apple Maggot

Plants affected - Apple, Evans Cherry, Hawthorn. Worse on early ripening apples.

Life Cycle:

  • Adults lay eggs in fruit early to mid July. Maggots make trails rendering fruit inedible (outside pockmarked)
  • Larvae drop to ground and pupate until the next June - July

Cultural Control:

  • Lay a barrier (landscape fabric, remay cloth) on top of soil under the tree—this prevents pupae from emerging from soil, as well as larvae entering soil in fall.
  • Apple Maggot Traps—hang in trees in mid-late May. Traps contain a pheromone to lure adults. Average emergence date in Alberta is July to August.
  • DO NOT allow fruit to lay on ground (use tarp or pick daily)

Chemical Control - None



Cherry Fruit Fly

Plants affected - Cherry

Symptoms - Larvae (maggots) feed in the flesh near the pit of cherries rendering them inedible.

Life Cycle:

  • Overwinter as pupae in soil under trees. Five to 9 days after emerging, adult female flies lay eggs singly in cherries.
  • Larvae feed for 1-2 weeks then cut exit hole and drop to ground to pupate.
  • Adults are present from June through August, generally peaking close to harvest. Flies are weak and will usually not travel farther than the first cherry tree they find.

Cultural Control - Hang yellow sticky traps in late May in trees to monitor fly emergence (for spraying date) and to trap adults.

Chemical Control - Sevin. Apply first spray no later than 6 days after capture of the first fly (on traps) followed by sprays at recommended intervals.

Gooseberry Sawfly

Plants affected - Red and White Currants (not black), Gooseberry

Symptoms - Leaves stripped from branches; fruit is not affected.

Life Cycle:

  • Female lays eggs on underside of leaf close to ground; young larvae make holes in leaves, as they mature damage becomes more severe; leaves are entirely stripped from shrub.
  • Overwinter in soil as a cocoon.

Cultural Control:

  • Examine leaves in May; look for white eggs low down in center of the bush, remove leaves.
  • Clear away debris and mulch in the fall, and disturb the soil in spring so birds will find them.

Chemical Control - Not recommended once larvae seen; try to destroy eggs early on.

Saskatoon Sawfly

Plants affected - Saskatoon


  • Small scars on upper part of green berries. Larger fruit may have holes.
  • Later in season fruit may appear as empty black shells.

Life Cycle:

  • Adults emerge in May, lay eggs on flowers. Eggs hatch, larvae emerge and feed on fruit.
  • In late June, larvae drop to ground and overwinter in soil.

Cultural Control - Look for adult sawflies when blooms emerge; hand-pick.

Chemical Control - Try a soil drench of Neem Oil in early May to treat larvae before emerging.

Wasp Damage

Plants affected - Soft skinned fruits

Symptoms - Clear sap oozing from sides of fruit

Control - Cover smaller trees with remay cloth as fruit is ripening, hang traps filled with sugar water/juice to distract wasps.